Recently, a lithium ion secondary battery (hereinafter, simply also referred to as a battery) is utilized as a power source for driving a hybrid vehicle or a portable electronic device such as a notebook-sized personal computer, a video camera corder, etc.
As one of such batteries, Patent Literature 1 discloses a lithium ion secondary battery in which a thermocouple is embedded in a predetermined portion of a battery main body (a power generating element).